IEEE Communications Magazine • November 2016
24
0163-6804/16/$25.00 © 2016 IEEE
AbstrAct
While there is clarity on the wide range of
applications that are to be supported by 5G cel-
lular communications, and standardization of
5G has now started in 3GPP, there is no con-
clusion yet on the detailed design of the overall
5G RAN. This article provides a comprehensive
overview of the 5G RAN design guidelines, key
design considerations, and functional innovations
as identified and developed by key players in the
field.
1
It depicts the air interface landscape that
is envisioned for 5G, and elaborates on how this
will likely be harmonized and integrated into an
overall 5G RAN, in the form of concrete control
and user plane design considerations and archi-
tectural enablers for network slicing, supporting
independent business-driven logical networks
on a common infrastructure. The article also
explains key functional design considerations for
the 5G RAN, highlighting the difference to leg-
acy systems such as LTE-A and the implications
of the overall RAN design.
IntroductIon
After several years of research on fifth genera-
tion (5G) wireless and mobile communications,
there is broad consensus that 5G will not just be
a “business-as-usual” evolution of 4G networks
with new spectrum bands, higher spectral effi-
ciencies, and higher peak throughput, but will
also target new services and business models. The
main 5G service types typically considered are
extreme mobile broadband (xMBB, a.k.a. eMBB)
with data rates up to several gigabits per second
in some areas and reliable broadband access
over large coverage areas, massive machine-type
communications (mMTC) requiring wireless con-
nectivity for, for example, millions of power-con-
strained sensors and actuators, and ultra-reliable
MTC (uMTC, a.k.a. ultra-reliable and low-laten-
cy communications, URLLC) requiring end-to-
end latencies of less than 5 ms and 99.999 percent
reliability for, say, vehicle-to-anything (V2X)
communication [1–3].
Investigations toward an overall 5G radio
access network (RAN) architecture that can
efficiently support these requirements are still
ongoing. This article provides an overview of the
5G RAN design guidelines, key design consider-
ations, and functional innovations identified and
developed by key players in the field.
1
Key 5G
RAN design requirements are listed, after which
the envisioned 5G air interface (AI) landscape
is described, including the latest considerations
on how different air interface variants (AIVs)
may be integrated into one overall AI. The arti-
cle further captures overall system architecture
considerations, such as the logical split between
core network (CN) and RAN and related net-
work interfaces, before venturing into key 5G
functional design paradigms. Finally, conclusions
are drawn.
Key 5G rAn desIGn requIrements
Due to the diverse and extreme requirements of
the main 5G service types, it is clear that the 5G
RAN must be designed to operate over a wide
range of spectrum bands with diverse characteris-
tics, such as channel bandwidths and propagation
conditions [1]. It must further be able to scale to
extremes w.r.t. throughput, number of devices,
connections, and so on, which is facilitated if the
user plane (UP), related to application payload
transmission, and control plane (CP), related to
control functionality and signaling, are handled
individually. For scalability also toward various
possible deployments and an evolving application
landscape, both 5G RAN and CN must be soft-
ware configurable, meaning, for example, that it
is configurable which logical and physical entities
are traversed by CP and UP packets.
A common understanding is that the 5G
RAN should allow integrating Long Term Evo-
lution-Advanced (LTE-A) evolution and novel
5G radio on the RAN level, although integration
need not always take place on this level.
The 5G RAN should further support more
sophisticated mechanisms for traffic differen-
tiation than LTE-A in order to fulfill diverse
and more stringent quality of service (QoS)
requirements, and facilitate the network slicing
vision from Next Generation Mobile Networks
(NGMN) [2], enabling independent operation of
logical networks for different business cases on a
shared physical infrastructure.
Another required feature distinctive from
LTE-A is the native and efficient support of
5G Radio Access Network Architecture:
Design Guidelines and Key Considerations
Patrick Marsch, Icaro Da Silva, Ömer Bulakci, Milos Tesanovic, Salah Eddine El Ayoubi, Thomas Rosowski, Alexandros Kaloxylos, and Mauro Boldi
5G rAdIo Access networK ArchItecture And technoloGIes
The authors provide a
comprehensive overview
of the 5G RAN design
guidelines, key design
considerations, and
functional innovations as
identified and developed
by key players in the
field. They depict the air
interface landscape that
is envisioned for 5G, and
elaborate on how this will
likely be harmonized and
integrated into an overall
5G RAN.
Patrick Marsch is with Nokia Bell Labs; Icaro Da Silva is with Ericsson AB; Ömer Bulakci and Alexandros Kaloxylos are with Huawei European Research Center;
Milos Tesanovic is with Samsung Electronics UK; Salah Eddine El Ayoubi is with Orange; Thomas Rosowski is with Deutsche Telekom AG;
Mauro Boldi is with Telecom Italia
1
Note that throughout the article,
any notion of “it is envisioned” or
“it is proposed” refers to the views
and proposals of partners of the
METIS-II project: www.metis-ii.5g-
ppp.eu/
Digital Object Identifier:
10.1109/MCOM.2016.1600147CM